``mutex`` --- Mutual exclusion support
**************************************
Deprecated since version The: ``mutex`` module has been removed in
Python 3.0.
The ``mutex`` module defines a class that allows mutual-exclusion via
acquiring and releasing locks. It does not require (or imply)
``threading`` or multi-tasking, though it could be useful for those
purposes.
The ``mutex`` module defines the following class:
class class mutex.mutex
Create a new (unlocked) mutex.
A mutex has two pieces of state --- a "locked" bit and a queue.
When the mutex is not locked, the queue is empty. Otherwise, the
queue contains zero or more ``(function, argument)`` pairs
representing functions (or methods) waiting to acquire the lock.
When the mutex is unlocked while the queue is not empty, the first
queue entry is removed and its ``function(argument)`` pair called,
implying it now has the lock.
Of course, no multi-threading is implied -- hence the funny
interface for ``lock()``, where a function is called once the lock
is acquired.
Mutex Objects
=============
``mutex`` objects have following methods:
mutex.test()
Check whether the mutex is locked.
mutex.testandset()
"Atomic" test-and-set, grab the lock if it is not set, and return
``True``, otherwise, return ``False``.
mutex.lock(function, argument)
Execute ``function(argument)``, unless the mutex is locked. In the
case it is locked, place the function and argument on the queue.
See ``unlock()`` for explanation of when ``function(argument)`` is
executed in that case.
mutex.unlock()
Unlock the mutex if queue is empty, otherwise execute the first
element in the queue.